Precursor is a chemical used in the manufacture of drugs that are in control. In general, the precursors used legally / officially in industrial processes and most traded in international trade.

The chemical is not in the special supervision, but the export and import and supply of precursors to individuals and companies whose use is not for use in industry is a clue that there is a possibility of these activities are illegal activities.

Precursor term used for materials that are not narcotic, but used in a variety of ways to process or make the narcotics or psychotropic substances.

Depending on their chemical properties, chemical precursors can be joined with other substances to be used as drug (or in the form of intermediaries), or can work as an acidic substance.

Here is a list of some of the precursors to manufacture legal drugs and materials commonly used in various industries.